[U-Boot] WIP for SPI

[Jon Loeliger]

On Tue, Jun 10, 2014 at 10:54 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Jon,
>
> I thought I should mention that I spent time on a flight to look at
> SPI with driver model. I have put the WIP code in branch 'working' in
> u-boot-dm.git. Note it doesn't work, and is very early. Also note that
> many of the patches have not been posted - I just want to make it
> clear what I am up to.

Awesome!

> In doing this I had to sort out the numbering of devices. U-Boot has
> the concept of SPI bus 2 on its command line, and for now at lest we
> need to keep that working. So I have added sequence numbers to devices
> - so a device can be considered 'child number 3' of its parent, for
> example. The numbers don't need to be sequential. I suppose we could
> generalise this to GPIOs if it works out.

And I think I am saying that we already *have* it generalized for
the GPIOs but only if we remove that renumbering function!

Consider again that the U_CLASS lookup of a GPIO simply matches
versus the range in each uclass data (gpio base and count).  That search
doesn't care about their order within the UCLASS_GPIO list.

(Never mind that the renumbering breaks the association of the device
base register and pin ranges as set up by the bind/probe code!)

> My approach for scanning the SPI bus in the device tree is similar to
> what I suggested a week or so ago - I took the code from dm_scan_fdt()
> and put it in a function with a udevice parent and node parameters. It
> seems to work OK for this simple case.

Nice!

Thanks,
jdl